1. Field of the Invention
The present invention relates to display lifting devices, and, more particularly, to a display lifting device having a mechanism of static equilibrium.
2. Description of Related Art
FIG. 1A shows a display lifting device as disclosed by Taiwan Patent No. M448598. Referring to FIG. 1A, the display lifting device has an elastic member 90, a fixed pulley 911, a connecting member 92, and a connecting rod 93. The fixed pulley 911 is rotatable about a first pivot axis 914 and has an arm-shaped rotating portion 912 disposed at a periphery thereof. The connecting rod 93 has one end connected to the elastic member 90 and the other end connected to the rotating portion 912 of the fixed pulley 911. The connecting member 92 has one end connected to the rotating portion 912 of the fixed pulley 911 and the other end connected to a lifting member (not shown) that carries a display. Further, a deflecting pulley 94 is provided to change the direction of the connecting member 92. Deformation of the elastic member 90 can apply a force to the rotating portion 912 at a distance from the first pivot axis 914 so as to produce a torque that is equal to a torque produced by gravity of the lifting member. As such, when the lifting member moves to cause the connecting member 92 to move, the position of the connecting rod 93 is changed, as shown in FIG. 1B, such that the whole mechanism reaches a static equilibrium and therefore the lifting member that carries the display can stop at any position.